1. Field of the Invention
The present invention relates to a multi-shaft driving apparatus comprising a plurality of motors for driving an articulated robotic hand or another plurality of operational shafts. More specifically, the present invention relates to a multichannel pulse train transmitting apparatus whereby the number of wires can be reduced in a multichannel pulse train transmission path for presenting a motor position command pulse train from a motor controller in the multi-shaft driving apparatus to motor drivers.
2. Description of the Related Art
In an articulated robotic hand or other multi-shaft driving apparatus, a plurality of motors, e.g., servo motors, are provided for driving the operational shafts; and position-detecting devices, e.g., rotary encoders, for detecting the rotation positions of the servomotors are attached to the servomotors. Based on a position command provided from a host computer or other device, and on an actual rotation position of the servo motors that is based on the detection signal from the rotary encoders, the motor controller of the multi-shaft driving apparatus generates motor position command pulses for controlling the driving of the servo motors, and presents the pulses to the motor drivers for controlling the driving of the servo motors.
A multichannel pulse train transmission path for presenting the position command pulse from the motor controller to the motor drivers is required in such a multi-shaft driving apparatus comprising a plurality of motors. When the number of motors increases, the number of channels (and therefore the number of signal wires) of the multichannel pulse train transmission path accordingly increases as well. If the number of signal wires can be reduced, the space through which the wires are extended need not be copious, wiring will be simplified, and the probability of wire breakage will be reduced.
DeviceNet, CAN, and various other standards for economizing on wiring between controllers and drivers are known. However, when these standards are used, a constraint is presented in that the driver must operate in accordance with the communication standard.
A configuration wherein communication between the controller and driver is performed using serial communication is disclosed in JP-A 2004-334551, JP-A 2002-366210, and JP-A 2002-171781. However, the method disclosed in JP-A 2004-334551 presupposes a configuration wherein the controllers and drivers correspond on a one-to-one basis, and is incompatible with the transmissions of a multichannel pulse train. The method disclosed in JP-A 2002-366210 presupposes a PC-based configuration that is compatible with serial communication. The method is used to transmit a pulse train position command, which is a command that transfers from a controller to a general motor driver, in only one direction. The method disclosed in JP-A 2002-171781 relates to serial communication between a controller and a PC, and does not relate to communication between a controller and a plurality of motor drivers.